MIC5283_12 Datasheet, PDF (9/19 Pages) Micrel Semiconductor – 120VIN, 150mA, Ultra-Low IQ, High-PSRR Linear Regulator

Micrel, Inc.
MIC5283
Detailed Description
The MIC5283 voltage regulator accepts a 6V to 120V input
voltage and has an ultra-low 8µA typical quiescent current
while offering an excellent line transient response and
PSRR. These features make it ideal for harsh, noisy
environments. All options offer 150mA of output current.
The MIC5283YML and MIC5283YME offer an adjustable
output voltage from 1.22V to 5.5V. The MIC5283-3.3YML
and MIC5283-3.3YME offer fixed 3.3V outputs and the
MIC5283-5.0YML and MIC5283-5.0YME offer fixed 5.0V
outputs. The YME packaged devices feature a heat slug to
more effectively remove heat from the die.
Applications Information
Thermal Protection
The MIC5283 has internal thermal shutdown to protect it
from excessive heating of the die. When the junction
temperature exceeds approximately +155°C, the output is
disabled and the device begins to cool down. The device
turns back on when the junction temperature cools by
15°C. This will result in a cycled output during continuous
thermal-overload conditions.
Current Limit
The MIC5283 features output current-limit protection. The
output sustains a continuous short circuit to GND without
damage to the device, but thermal shutdown often results.
The typical value for the current limit of the MIC5283 is
300mA.
Input Capacitor
Connect a 1.0µF capacitor from VIN to GND. Micrel
recommends the C5750X7R2E105M, 1.0µF, 250V
capacitor made by TDK. When using a different capacitor,
assure that the voltage rating of the capacitor has
adequate headroom to withstand any potential transient.
CPSRR Capacitor
To maintain high power supply rejection, connect a 0.1µF
capacitor from CPSRR to GND. The voltage rating of the
capacitor must be at least 14V.
Output Capacitor
Connect a 10µF capacitor from VOUT to GND. Assure that
the voltage rating of the capacitor exceeds the designed
output voltage of the MIC5283.
Output Voltage Setting
For the MIC5283YML and MIC5283YME, V_OUT is
programmable from 1.22V to 5.5V using an external
resistive divider. V_OUT is set using the following equation:
V_OUT

V_REF



R1
R2

1

where V_REF = 1.22V, and R1 and R2 form the feedback
voltage divider from V_OUT to ground.
Thermal Measurements
It is always prudent to measure an IC’s case temperature
to make sure that it is within operating limits, but it is easy
to get erroneous results. The standard thermocouple that
comes with many voltage meters uses a large wire gauge
that behaves like a heat-sink, resulting in artificially low
case temperature measurements. Use a thermocouple of
36-gauge wire or smaller, such as the Omega (5SC-TT-K-
36-36), to minimize the heat-sinking effect. Also, apply a
thermal compound to maximize heat transfer between the
IC and the thermocouple.
An infrared thermometer is a recommended alternative.
The IR thermometer from Optris has a 1mm spot size,
ideal for monitoring small surface mount packages. Also,
the optional stand makes it easy to keep the beam on the
IC for long periods of time.
March 2012
9
M9999-030812-A